Switch-key.



G. P. TROMP.

SWITCH KEY.

APPLICATION FII BD FBB.1 O, 1914.

Patented Sept. 8, 1914.

p. W mm H. ,w y D UNITED STATESPATENT OFFICE.

GERARD PIETER 'TROMP, OF NEW YORK, N. Y., ASSIGNOR-TO WESTERN ELECTRICCOMPANY, OF NEW YORK, Y., A CORPORATION OF ILLINOIS.

SWITCH-KEY.

Specification of Letters Patent.

Patented Sept. 8, 1914 To all whom it may concern Be it known that I,GERARD PIETER TROMP, a subject of the Queen of the Netherlands, residingat New York, in the county of New York and State of New York, haveinvented a certain' new and useful Improvement in Switch-Keys, of whichthe following is a full, clear, concise, and exact description.

This invent-ion relates to telephone keys, and more particularly to whatare known as listening and ringing keys.

The object of the invention isto provide a cushioning means to preventthe rebound or blow of the key lever when restored to normal positionfrom opening the normally closed contacts of the'key.

In accordance with the invention, one or more of the master switchsprings, that is, those engaged by the operating means, are providedwith a yielding portion which is engaged by the operating roller toprevent the bodily movement of said springs out of contact with theirengaging contacts until said lever has been moved a considerabledistance out of normal. This resilient means comprises a loop formed ofthe ends of the master contact springs, said loop being normally closedso as to limit the amount of flexure in the loop itself when compressedby the operating roller; and so shaped that the loop is distorted out ofnormal position when engaged by the actuating roller before the bodilymovement of the said master springs begins.

In the accompanying drawings,Figure 1 is a perspective view showing aswitch key embodying this invention; Fig. 2 is a vertical section takenon line 22 of Fig. 3; Figs. 3, 4 and 5 are side elevations, showing .thekey in a normal, listening and ringing position, respectively. p Likeparts are designated by similar reference characters throughout theseveral views. i

The structure shown comprises a top plate 1', supporting a switchactuating rocking lever 2. Associated with the key is a supporting frameof inverted U-shape, having downwardly extending arms 4, 4, which areunited by, abridging member or rib 7, upon either side whereof springpile-up units 6, 6, are mounted by means 0 blocks 8, 8. Said units arepositioned so as to hold the contact springs in operative relation withthe actuating rollers.

The means provided for cushioning the operating lever consists of masterspring members 11, 12, formed at the top -into flexible loops l3,14,-said loops being normally closed. The spring ends 15 projecting fromthe loops bear against the plunger rollers 16, 17, unless the key lever2 is in an operated position, in which case one or the otherof saidprojecting ends will be disengaged. When one of said extensions 15 isdisengaged, the resiliency of the metal causes a gap to form at the neckof the loop as shown in Fig. 4. Fig. 3 shows the master spring members11, 12 with the key plunger in a normal position. \Vhen the key is-inthis position, there is a slight pressure exerted against the plungerrollers 16, 17 by the terminals 13, 14 of said master spring member,which tend to hold the key in said position. Figs. 4 and 5 show the keyin an operated position, whereby one or the other of the master springmembers is disengaged.

When the lever 2 is operated it may be moved a, considerable distancebefore contacts that are normally closed are interrupted, and contactsthat are normally open become closed. Upon the actuation of the lever,one of the plunger rollers engages the extension of one of the loopshaped top portions, causing said loop shaped portion in contact withthe roller to change its angular position in regard to the lever rolleruntil a position is reached where no further change takes place, whichin a locking key is a short distance .from the end of the stroke. Duringthe time thatthe lever is re turning when released, this same movementis again gone through, except that, of course, it is reversed. Thecombined action of the spring and roll prevents the lever from quicklyreleasing'until it has been manually moved nearly to its normalposition. It is thus possible to obtain a relatively slow release for amajor part of the stroke, and a quick release for the last part, as aresult of which the blow of the plunger striking the opposite set ofsprings is considerably lessened.

During the compression of the loop shaped top portion upon the operationof the key lever, the ro ecting end 15 comes to rest upon shou der 18formed in the master spring member at the point where the loop is madein said master spring member, thus reinforcing the part of the springincluded in the loop and, by limiting the amount of flexure in the looitself, greatly relieving the elastic stress w' ich would otherwise beexerted upon the metal. By thus reducing the elasticstrain upon thepart'of the spring forming the loop shaped top portion, the life of themaster spring member is greatly prolonged.

By the means provided in this invention, Whenever the lever 2 isreturned from an operated to normal position, a cushioning eifect justbefore, the end of the stroke is obtained when the plunger strikes theopposite ornnoperated master spring member, and by efiecting a slightcompression in it. This cushioning effect absorbs the shock of theplunger, thereby preventing the opening of contact springs normallyclosed, thus eliminating any disagreeable disturbance in the lineconnection.

What is claimed is:

1. In a key switch, the combination with a pair of normally closedcontact springs, of a roller adapted to engage one of said springs toseparate said contacts, theengaged portion of said spring being formedinto, a normally closed resilient loop, said roller in its engagementwith said loop first acting against the resilience of said 100 to absorbthe inertia of-said rollerand t enacting against the pressure of saidswitch spring to open the contacts.

2. In a key switch, a group of contact springs embracing a mastercontact member,

an operating lever, a loop shaped portionon said master contact member,said loop having an extension thereon, a shoulder formed where said loopis made in said contact member against which said extension engagesunder pressure of said operating lever.

springs embracing a master contact member,

an operating device, said master contact member having a resilient loopshapedportion, said portion being normally engaged and closed by saidoperating devic'e,=. said loop on said portion having a gap at its,

neck when said top portion is disengaged by said operating device,whereby "a cushionin' eflect is obtained to absorb the shock of saioperating device when said operating device is returned from an operatedto normalposk tion: i i l 5. A master spring contact member hav; ing aloop shaped portion, said loop shaped portion having an extensionthereon, and said contact member having a shoulder formed wheresaid=loop is made, said shoulder functioning as a stop for saidextension when said loop is compressed 6. Ina key switch, a switchspringhaving one end secured to the switch frame and having its free endformed into 'a resilient loop,

and an operating device normally engaging and closing said loop.

In witness whereof, I hereunto subscribe my name this 6th day of-February A. D.,

GERARD PIETER TROMP.

W'itnesses J. F. EBERT, M. V. CONATY.

